EAS Compressor not cutting in

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I would appreciate some advice.

My 1995 P38 4.6 HSE has had a suspension problem for over a year. (as you can see by my previous request for help)

EAS Compressor will not cut in. Tried a known working compressor but same fault therefore I assume heat sensor is OK in mine. Bought new sensor which fits under valve block ~ fitted ~ same problem compressor not cutting in. When the Beast lowers, I jump the fusebox relay to get her back up. Had a severe water leak through windscreen, new screen now fitted and my suspicion is that wires have corroded therefore no power to compressor on switching. (Bear with me I'm not a techie!)

This what I'm thinking of doing and I would like some advice to see if it makes sense.

!). jumping the relay works

2). as the relay is essentially a switch why not replace it with a switch with a cable through to the dash with dash switch warning light?

3). When EAS dash lights start flashing I would flick the switch to activate compressor until EAS is normal

Would doing this cause any harm for instance to the engine bay fuse box?

Any other thoughts?

Trying to avoid any expense as I'm a pensioner with limited income.
 
Last edited:
maelstrompat said:
I would appreciate some advice.

My 1995 P38 4.6 HSE has had a suspension problem for over a year. (as you can see by my previous request for help)

EAS Compressor will not cut in. Tried a known working compressor but same fault therefore I assume heat sensor is OK in mine. Bought new sensor which fits under valve block ~ fitted ~ same problem compressor not cutting in. When the Beast lowers, I jump the fusebox relay to get her back up. Had a severe water leak through windscreen, new screen now fitted and my suspicion is that wires have corroded therefore no power to compressor on switching. (Bear with me I'm not a techie!)

This what I'm thinking of doing and I would like some advice to see if it makes sense.

!). jumping the relay works

2). as the relay is essentially a switch why not replace it with a switch with a cable through to the dash with dash switch warning light?

3). When EAS dash lights start flashing I would flick the switch to activate compressor until EAS is normal

Would doing this cause any harm for instance to the engine bay fuse box?

Any other thoughts?

Trying to avoid any expense as I'm a pensioner with limit income.
Click to expand...
You could use a switch but better to fix it. I haven't read the whole thread but bad connections are common cause assuming that the replacement compressor really was OK.
First step would be to use the free EAS sofware diagnostics to see if the pump can be switched on in diagnostics. If it can then it eliminates some of the wiring and possibly the fuse box. Depending on the outcome more advice can be given.
 
Do the thermal switch continuity checks on compressors as previously posted. Make sure the simple fixes are all covered before you go complex. If you don't understand electrics find someone who does. Pretty simple process of elimination if not a little tedious.
 
maelstrompat said:
My local garage (Power Crazy Motorsports) put a multimeter on the Orange wire today and said it was OK but I don't think they attached a wire to earth and as I said, we also borrowed another pump which was certified OK (thermal switch etc.) and had the same prob.
Click to expand...

I kept chasing my tail for weeks if not months because of this.

Exact same symptoms as you are getting.
I pulled the compressor apart in the end after I had ordered a new thermal switch. I found bad connections inside, cannot remember which, but probably the dreaded orange wire. As I was still going to change the switch anyway when it came to the rebuild I re soldered it. All as good as gold since.
 
maelstrompat said:
I would appreciate some advice.

My 1995 P38 4.6 HSE has had a suspension problem for over a year. (as you can see by my previous request for help)

EAS Compressor will not cut in. Tried a known working compressor but same fault therefore I assume heat sensor is OK in mine. Bought new sensor which fits under valve block ~ fitted ~ same problem compressor not cutting in. When the Beast lowers, I jump the fusebox relay to get her back up. Had a severe water leak through windscreen, new screen now fitted and my suspicion is that wires have corroded therefore no power to compressor on switching. (Bear with me I'm not a techie!)

This what I'm thinking of doing and I would like some advice to see if it makes sense.

!). jumping the relay works

2). as the relay is essentially a switch why not replace it with a switch with a cable through to the dash with dash switch warning light?

3). When EAS dash lights start flashing I would flick the switch to activate compressor until EAS is normal

Would doing this cause any harm for instance to the engine bay fuse box?

Any other thoughts?

Trying to avoid any expense as I'm a pensioner with limited income.
Click to expand...

I did this too, that is how I managed to get by for so long before repairing it properly. I just had a suitable switch mounted up in the cab, it was ok, but as I was leaking air a little it needed regular switching, end result was beep beep beep EAS fault at the most inconvenient of times, like 5 mins before an MOT.
 
Datatek said:
You could use a switch but better to fix it. I haven't read the whole thread but bad connections are common cause assuming that the replacement compressor really was OK.
First step would be to use the free EAS sofware diagnostics to see if the pump can be switched on in diagnostics. If it can then it eliminates some of the wiring and possibly the fuse box. Depending on the outcome more advice can be given.
Click to expand...

Thanks for your response.
Easi-unlock powers the compressor OK (I either jump the relay or plug in my laptop to get the compressor working)
 
wammers said:
Do the thermal switch continuity checks on compressors as previously posted. Make sure the simple fixes are all covered before you go complex. If you don't understand electrics find someone who does. Pretty simple process of elimination if not a little tedious.
Click to expand...

Thanks for your response.
Yes, if you mean the Orange wire check that was done.
Earlier post:
Originally Posted by maelstrompat View Post
My local garage (Power Crazy Motorsports) put a multimeter on the Orange wire today and said it was OK but I don't think they attached a wire to earth and as I said, we also borrowed another pump which was certified OK (thermal switch etc.) and had the same prob.
 
Last edited:
JamesBB said:
I kept chasing my tail for weeks if not months because of this.

Exact same symptoms as you are getting.
I pulled the compressor apart in the end after I had ordered a new thermal switch. I found bad connections inside, cannot remember which, but probably the dreaded orange wire. As I was still going to change the switch anyway when it came to the rebuild I re soldered it. All as good as gold since.
Click to expand...

Thanks for your response.
The problem is that when a known - good compressor was fitted (to check to see if the original was duff) it also would not cut-in.
 
maelstrompat said:
Thanks for your response.
The problem is that when a known - good compressor was fitted (to check to see if the original was duff) it also would not cut-in.
Click to expand...

This problem happened not to long ago where the known good compressor was duff. You MUST have solid continuity from orange wire to black wire on compressor plug. Not a resistance measurement but solid zero resistance continuity.
 
wammers said:
This problem happened not to long ago where the known good compressor was duff. You MUST have solid continuity from orange wire to black wire on compressor plug. Not a resistance measurement but solid zero resistance continuity.
Click to expand...

Wammers ~ Thanks, I will get it checked again by a different auto-electrician.
 
Datatek said:
If EAS unlock powers the compressor, then it has to be the thermal switch or the connection from the thermal switch to the ECU.
Click to expand...


Connection from thermal switch to ECU makes sense but I had that checked and replaced the ECU and I was thinking perhaps the connection under the passenger seat (BECM ?) or between there and the compressor and not the ECU. I've got a multimeter but not sure what setting apart from resistance to use.
 
maelstrompat said:
I would appreciate some advice.

This what I'm thinking of doing and I would like some advice to see if it makes sense.

!). jumping the relay works

2). as the relay is essentially a switch why not replace it with a switch with a cable through to the dash with dash switch warning light?

3). When EAS dash lights start flashing I would flick the switch to activate compressor until EAS is normal

Would doing this cause any harm for instance to the engine bay fuse box?

Any other thoughts?

Trying to avoid any expense as I'm a pensioner with limited income.
Click to expand...

If you do fit this switch also fit an air pressure guage in the dash. Then you can see when you need air. I have this fitted and usually maintain the air at 60-120psi. There is no need imo for the high pressure it normally runs at. If you wait for the flashing lights you will be too late, it will go into fault.
 
mgmayo said:
If you do fit this switch also fit an air pressure guage in the dash. Then you can see when you need air. I have this fitted and usually maintain the air at 60-120psi. There is no need imo for the high pressure it normally runs at. If you wait for the flashing lights you will be too late, it will go into fault.
Click to expand...

Many thanks, how did you set yours up? 'T' connector below compressor on air pipe?
 
wammers said:
This problem happened not to long ago where the known good compressor was duff. You MUST have solid continuity from orange wire to black wire on compressor plug. Not a resistance measurement but solid zero resistance continuity.
Click to expand...

maelstrompat said:
Connection from thermal switch to ECU makes sense but I had that checked and replaced the ECU and I was thinking perhaps the connection under the passenger seat (BECM ?) or between there and the compressor and not the ECU. I've got a multimeter but not sure what setting apart from resistance to use.
Click to expand...


resistance is the thing to check, take plug apart and DIY, please get it sorted without switch and gauge

and make sure you connected the new pressure switch correctly and it's working
 
Last edited:
Druim said:
resistance is the thing to check, take plug apart and DIY, please get it sorted without switch and gauge

and make sure you connected the new pressure switch correctly and it's working
Click to expand...

Agree with this too. The time and effort and cost will be better placed fixing it. Check the connection and termination of the orange wire in the compressor. You need to take the end off of it, but no need to remove the printed circuit to check the connection.
 
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